ironwood.live
ZEC —

ZCASH · NU6.3 IRONWOOD · BLOCK 3,428,143

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ORCHARD

—

closed to inflows at activation

IRONWOOD

—

opens at block 3,428,143

At activation, Orchard permanently closes to inflows (ZIP 258). The only way forward is through the turnstile — and every crossing amount is publicly counted.

Where all 16.8M ZEC sits

Lockbox is the protocol-held dev-fund reserve, not user funds. Shielded total: — ZEC.

Orchard drains, Ironwood fills

Orchard Ironwood

Why Zcash built a turnstile

01

A soundness bug hid in Orchard for four years

On May 29, 2026, Taylor Hornby discovered a critical counterfeiting vulnerability in the Orchard shielded pool — present since May 2022 — that “could have been exploited to undetectably create an unlimited amount of counterfeit ZEC.” An emergency fix shipped June 1–3 (NU6.2 hard fork at block 3,364,600); the bug was disclosed June 4 by Zooko Wilcox, Jason McGee and Taylor Hornby. Their assessment: “Prior Exploitation Of This Orchard Vulnerability Seems Unlikely.” ZEC fell from ~$602 to ~$299 on disclosure. Read the disclosure →

02

The turnstile proves the supply is sound

“Seems unlikely” is not proof. So NU6.3 Ironwood creates a fresh pool (same Orchard protocol, fresh state, v6 transactions) and permanently blocks inflows to old Orchard — per ZIP 258, its balance can only go down. “By restricting payments in the old pool, we force any hypothetical counterfeit coins to travel through the turnstile before wallets accept them as payment.” The monitoring principle is simple: as long as the value in the shielded pools stays above zero, no counterfeiting has been detected. That is exactly the number this site watches.

03

What a crossing reveals — and what it doesn’t

A migration is a single v6 transaction: an Orchard spend into an Ironwood output. The amount crossing is publicly revealed through the transaction’s value-balance fields; the sender, receiver and individual notes stay shielded. Same semantics as the historical Sprout→Sapling turnstile. Migration is open-ended — no deadline — and existing Orchard addresses keep working: wallets simply deliver new payments to Ironwood, and ZIP 2005 advises migrating all funds (transparent, Sprout and Sapling too) into Ironwood recoverable notes.

The race caveat

The turnstile floors the old pool at zero. If counterfeits did exist, whoever exits through the turnstile first consumes the available exit capacity — late migrators of a compromised pool could find themselves unable to exit. One more reason wallets urge migrating early rather than someday.

Quantum-recoverable ≠ quantum-proof

Ironwood notes are quantum-recoverable (ZIP 2005): if the discrete log ever breaks, a Recovery Protocol can recover Ironwood funds — but not Sprout, Sapling or Orchard funds. That is not the same as quantum-resistant privacy. Full post-quantum work is Project Tachyon, targeted at the NU7 era. Ironwood is NU6.3, and it does not make ZEC quantum-safe.

Sprout’s lesson: turnstiles have long tails

Zcash has done this before. Sprout had its own counterfeiting flaw (found March 2018, fixed by Sapling that October, disclosed February 2019) — and nearly eight years later, ~25,409 ZEC still sits in Sprout, never having crossed. The official post-mortem describes that residual as funds that “may be abandoned or lost”. Expect the Orchard→Ironwood curve to climb fast, then crawl — turnstile migrations never quite reach 100%. The Sprout story →

Who’s ready

Embed this tracker

A compact live card — countdown now, percentage after activation. Drop it anywhere iframes work:

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  width="340" height="210" loading="lazy"
  style="border:0;border-radius:12px;overflow:hidden"
  title="ironwood.live — Zcash Ironwood migration tracker"></iframe>